Why It's Prescribed

Under the brand name Prozac, fluoxetine is prescribed for depression, obsessive-compulsive disorder, some eating disorders, and panic attacks.[2] Additionally, it is prescribed under the brand name Sarafem for premenstrual dysphoric disorder.

Form, Route, and Dosage

Fluoxetine is available as a capsule, a tablet, a delayed-release (long-acting) capsule, and a solution (liquid) to take orally.[5] It is available as a solution in the strength 20mg/5ml and as a tablet or capsule in the strengths 10mg, 20mg, and 40mg.[6] Under the brand name Sarafem, it is only available in the strengths 10mg and 20mg. Adults are generally instructed to take between 10mg and 80mg of fluoxetine per day.[7]

Warnings

"A small number of children, teenagers, and young adults (up to 24 years of age) who took antidepressants ('mood elevators') such as fluoxetine during clinical studies became suicidal (thinking about harming or killing oneself or planning or trying to do so). Children, teenagers, and young adults who take antidepressants to treat depression or other mental illnesses may be more likely to become suicidal than children, teenagers, and young adults who do not take antidepressants to treat these conditions. However, experts are not sure about how great this risk is and how much it should be considered in deciding whether a child or teenager should take an antidepressant.

"You should know that your mental health may change in unexpected ways when you take fluoxetine or other antidepressants even if you are an adult over 24 years of age. You may become suicidal, especially at the beginning of your treatment and any time that your dose is increased or decreased. You, your family, or your caregiver should call your doctor right away if you experience any of the following symptoms: new or worsening depression; thinking about harming or killing yourself, or planning or trying to do so; extreme worry; agitation; panic attacks; difficulty falling asleep or staying asleep; aggressive behavior; irritability; acting without thinking; severe restlessness; and frenzied abnormal excitement. Be sure that your family or caregiver knows which symptoms may be serious so they can call the doctor if you are unable to seek treatment on your own."

As a Pollutant

Because humans and animals often do not fully metabolize pharmaceuticals in their body, they can excrete drugs or their breakdown products, which may the enter the environment.[11]

In Sewage Sludge

Fluoxetine has been found in sewage sludge. In the Targeted National Sewage Sludge Survey, a 2009 test of 84 samples of sewage sludge from around the U.S., the EPA found fluoxetine in 79 samples (94%) in concentrations ranging from 12.4 to 3,130 parts per billion.[12] There are no federal regulations governing how much of this drug may be present in sewage sludge applied to land as fertilizer.

Plant Uptake of Sludge Contaminants

Several pharmaceuticals are routinely found in sewage sludge and effluent from wastewater treatment plants, which are then used to fertilize or irrigate farm fields. A study by researchers at the University of Toledo simulated both fertilization with sewage sludge and irrigation with wastewater laced with three three pharmaceuticals, carbamazepine, diphenhydramine, and fluoxetine, and two personal care products, triclosan and triclocarban, to then examine their uptake by soybean plants.[13] The study found that, "with the exception of fluoxetine, all of the chemicals accumulated in the plant tissues from exposure to both wastewater and biosolids."[14]

In Drinking Water

An Associated Press investigation found that, of 62 metropolitan areas in the U.S., only 28 tested for pharmaceuticals, and 24 found pharmaceuticals in the drinking water when they tested it.[15] Of those tested, Philadelphia tested positive for fluoxetine (as well as 55 other drugs).[16]

Toxicity in Wildlife

In 2010, NPR reported that fluoxetine released into waterways affects shrimp:[17] "When a drug like Prozac bumps up a shrimp's serotonin levels, the crustacean is much more likely to abandon shadowy, safe waters and swim toward the light, where it makes a tempting target for predators." Fluoxetine in shrimp "mimics the action of a parasite that infests shrimp" by making the shrimp swim toward the light, making the shrimp "more likely to put themselves in mortal danger."